Apparatus and method for determining information on a power variation of a transmit signal

ABSTRACT

An apparatus for determining information on a power variation of a transmit signal comprises a power amplifier module, an antenna module and a power variation determining module. The power amplifier module amplifies a radio frequency transmit signal and the antenna module transmits at least partly the amplified radio frequency transmit signal. The power variation determining module determines a weighted sum of a first feedback signal derived from the amplified radio frequency transmit signal and a second feedback signal derived from the amplified radio frequency transmit signal. The first feedback signal and the second feedback signal comprise different dependencies on a varying impedance at the antenna module. Further, the power variation determining module generates a power variation signal based on the weighted sum. The power variation signal comprises information related to a power variation of the amplified radio frequency transmit signal.

PRIORITY APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/341,115, filed Jul. 25, 2014, which claims the benefit of priority toGerman Application No. 102013108128.2, filed Jul. 30, 2013, each ofwhich is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to the determination of properties ofelectrical signals and in particular to an apparatus and a method fordetermining information on a power variation of a transmit signal.

BACKGROUND

The power amplification of electrical signals is an often necessarytask, especially if signals are transmitted over long distances (e.g.wireless). For example, the power amplifier (PA) in a mobile terminalhas to cope with a wide range of load impedances, since the antennaimpedance is heavily affected by instantaneous environmental conditions(e.g. free space, antenna covered by hand). Many power amplifiers areoptimized for 50Ω conditions and also power amplifier specification maynot care about mismatch (e.g. despite requirements for ruggedness andstability). For instance, the power variation into a non-50Ω antennaload may be neglected, which increases the effort for antenna and radiofrequency (RF) engine design (e.g. to optimize post power amplifiermatching and antenna matching).

Since the radiated power is often not satisfying, the network operatorsstarted to define specific requirements (so-called total radiated powerrequirements, TRP), especially in area where the coverage is minimal.One related requirement may be the power variation into voltage standingwave ratio (VSWR, output power ripple caused by non-50Ω antennaimpedance). It is desired to minimize the power variation into mismatch.

BRIEF DESCRIPTION OF THE FIGURES

Some examples of apparatuses and/or methods will be described in thefollowing by way of example only, and with reference to the accompanyingfigures, in which

FIG. 1 shows a block diagram of an apparatus for determining informationon the power variation of a transmit signal:

FIG. 2 shows a block diagram of a further apparatus for determininginformation on a power variation of a transmit signal:

FIG. 3 shows a block diagram of a further apparatus for determininginformation on a power variation of a transmit signal;

FIG. 4 shows a block diagram of a mobile device:

FIG. 5a shows a flowchart of a method for determining information on thepower variation of a transmit signal; and

FIG. 5b shows a flowchart of a further method for determininginformation on a power variation of a transmit signal.

DETAILED DESCRIPTION

Various examples will now be described more fully with reference to theaccompanying drawings in which some examples are illustrated. In thefigures, the thicknesses of lines, layers and/or regions may beexaggerated for clarity.

Accordingly, while examples are capable of various modifications andalternative forms, the illustrative examples in the figures and willherein be described in detail. It should be understood, however, thatthere is no intent to limit examples to the particular forms disclosed,but on the contrary, examples are to cover all modifications,equivalents, and alternatives falling within the scope of thedisclosure. Like numbers refer to like or similar elements throughoutthe description of the figures.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it can be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. Other words used to describe therelationship between elements should be interpreted in a like fashion(e.g., “between” versus “directly between,” “adjacent” versus “directlyadjacent,” etc.).

The terminology used herein is for the purpose of describingillustrative examples only and is not intended to be limiting. As usedherein, the singular forms “a,” “an” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises,”“comprising,” “includes” and/or “including,” when used herein, specifythe presence of stated features, integers, steps, operations, elementsand/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which examples belong. It will befurther understood that terms, e.g., those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

FIG. 1 shows a block diagram of an apparatus 100 for determininginformation on a power variation of a transmit signal. The apparatus 100comprises a power amplifier module 110, an antenna module 120 and apower variation determining module 130. The power amplifier module 110amplifies a radio frequency transmit signal 102 and the antenna module120 transmits at least partly the amplified radio frequency transmitsignal 112. The power variation determining module 130 determines aweighted sum of a first feedback signal 116 derived from the amplifiedradio frequency transmit signal 112 and a second feedback signal 118derived from the amplified radio frequency transmit signal 112. Thefirst feedback signal 116 and the second feedback signal 118 comprisedifferent dependencies on a varying impedance at the antenna module 120.Further, the power variation determining module 130 generates a powervariation signal 132 based on the weighted sum so that the powervariation signal 132 comprises information related to a power variationof the amplified radio frequency transmit signal 112.

By calculating a weighted sum of two signals derived from a radiofrequency transmit signal 112 but with different dependencies on animpedance at the antenna module 120, an influence of variations of theimpedance at the antenna module 120 or the weighted sum (e.g. which mayvary due to varying environmental conditions) can be kept low or evencompletely removed. In this way, an information on the power variationof the amplified radio frequency transmit signal 112 can be determinedwithout a contribution of the varying impedance at the antenna module120 or with negligible contribution of the varying impedance at theantenna module 120. In other words, due to the consideration of theweighted sum, information on a power variation for a nearly perfectly ora perfectly matched antenna module can be provided. Such information maybe used for the control of the gain of the power amplifier module 110without or with negligible influence of the variation of the impedanceat the antenna module 120. In this way, the power variation intomismatch may be significantly reduced, for example.

The radio frequency transmit signal 102 may be provided by an arbitrarysource. For example, the radio frequency transmit signal 102 may beprovided by a modulator module (e.g. in-phase/quadrature-phase modulatoror polar modulator) generating the radio frequency transmit signal 102by an up-conversion from a baseband domain (e.g. frequencies below 100MHz) to a radio frequency domain (e.g. frequencies between 500 MHz and10 GHz). The up-conversion may be done at least by mixing acomplex-valued baseband transmit signal with a carrier signal (e.g. alocal oscillator signal). The resulting radio frequency transmit signal102 may comprise a frequency bandwidth located in the region of thefrequency of the carrier signal.

The radio frequency transmit signal 102 may be a test signal fordetermining information on the power variation of the amplified radiofrequency transmit signal 112 or may contain information intended to betransmitted to a receiver, for example. In this way, information on apower variation of the amplified radio frequency transmit signal 112 canbe determined in a test state and/or in an operating state (e.g. whiletransmitting information to be received by a receiver) of the apparatus100.

The power amplifier module 110 amplifies the radio frequency transmitsignal 102. For this, the power amplifier module 102 may comprise atleast a power amplifier circuit. Optionally, the power amplifier module110 may comprise further elements for providing the amplified radiofrequency transmit signal 112 with high quality (e.g. power amplifiercore, controller, matching module, bias feed and/or one or more filterelements).

The power amplifier module 110 may amplify the radio frequency transmitsignal 102 so that the amplified radio frequency transmit signal 112 canbe transmitted to a receiver through the antenna module 120 withsufficient transmit power.

The antenna module 120 transmits at least partly the amplified radiofrequency transmit signal 112. Depending on the matching of the antennamodule 120 and/or the environmental conditions in the proximity of theantenna module 120 and/or the way the feedback signals are derived fromthe amplified radio frequency transmit signal 112, the whole amplifiedradio frequency transmit signal 112 is transmitted or a part of theamplified radio frequency transmit signal 112 is reflected due tomismatch or is used for deriving the first feedback signal 116 and/orthe second feedback signal 118, for example. The antenna module 120 maycomprise one or more antennas (e.g. one antenna forsingle-input-single-output communication, multiple antennas formultiple-input-multiple-output communication).

The first feedback signal 116 and the second feedback signal 118 arederived from the amplified radio frequency transmit signal 112. A signalmay be derived from the amplified radio frequency transmit signal 112 invarious ways. For example, a coupling element may be located in theproximity of a transmit path between the power amplifier module 110 andthe antenna module 120 so that the coupling element provides a singlecorrelated to the amplified radio frequency transmit signal 112 due tocapacitive and/or inductive coupling. For example, a coupling elementmay be a capacitor or a directional coupler.

Such a coupling element may provide the first feedback signal 116 and/orthe second feedback signal 118 itself or may provide a signal to beprocessed in order to obtain the first feedback signal 116 and/or thesecond feedback signal 118. In both cases, the first feedback signal 116and the second feedback signal 118 is derived from the amplified radiofrequency transmit signal 112. In other words, the first feedback signal116 and the second feedback signal 118 may comprise signal portionsrelated to the amplified radio frequency transmit signal and a reversewave signal caused by a reflection of the amplified radio frequencytransmit signal 112 due to a varying impedance mismatch at the antennamodule 120.

Both feedback signals are derived from the amplified radio frequencytransmit signal 112 so that both signals comprise a dependency on avarying impedance at the antenna module 120. However, the first feedbacksignal 116 comprises a dependency on the varying impedance at theantenna module 112 (e.g. a larger or lower portion related to a signalreflected due to mismatch) different from a dependency on the varyingimpedance at the antenna module 120 of the second feedback signal 118.For example, feedback signals with different dependencies on the varyingimpedance at the antenna module 120 may be obtained by deriving thefirst feedback signal 116 and the second feedback signal 118 atdifferent positions within the transmit path between the power amplifiermodule 110 and the antenna module 120 or obtained the signals atdifferent ports of a directional coupler within the transmit pathbetween the power amplifier 110 and the antenna module 120.

The impedance at the antenna module 120 may be an impedance observed orperceived at a connection or terminal (e.g. pin) of the antenna module120 connecting the antenna module 120 to the transmit path. This varyingimpedance at the antenna module 120 may be representable by an impedanceof the antenna module 120 (e.g. frequency-dependent but constant in timefor constant frequency) and a temporarily varying impedance due tovarying environmental conditions in the proximity of the antenna module120 (e.g. free space or antenna covered by a moving object).

The power variation determining module 130 determines the weighted sumof the first feedback signal 116 and the second feedback signal 118. Theweighted sum may represent a sum of the first feedback signal 116weighted by a weighting factor and the second feedback signal 118 or asum of the first feedback signal 116 and the second feedback signal 118weighted by a weighting factor. The weighted sum may be calculated ordetermined continuously (e.g. if the first feedback signal and thesecond feedback signal are analog signals) or may be determined orcalculated over a predefined number of samples of the first feedbacksignal 116 and the second feedback signal 118 (e.g. if the firstfeedback signal and the second feedback signal are digital signals).

In the following, the second feedback signal 118 may be weighted by aweighting factor, although a weighting of the first feedback signal 116or a weighting of both feedback signals (e.g. by different weightingfactors) may also be possible.

Additionally, the power variation determining module 130 generates thepower variation signal 132 comprising information related to a powervariation of the amplified radio frequency transmit signal 112.Information related to the power variation of the amplified radiofrequency transmit signal 112 may be represented in various ways. Forexample, the information may indicate a change of an average outputpower of the power amplifier module 110 over time (e.g. arithmetic meanor root mean square) or an average output power of the power amplifiermodule 110 (e.g. arithmetic mean or root mean square) or a currentoutput power of the power amplifier module 110 or a maximal, minimal oraverage variation of the output power of the power amplifier module 110over a predefined time interval. For example, the power variationdetermining module 130 may generate the power variation signal 132 basedon a root mean square calculation of the weighted sum over a predefinedtime interval (e.g. for a predefined number of temporarilysuccessively-calculated weighted sums). In other words, the powervariation signal may contain information on the root mean square of thedetermined weighted sum. In this way, information related to a powervariation of the amplified radio frequency transmit signal 112 over timecan be provided with low effort and/or in real time.

The power variation determining module 130 may determine the weightedsum in various ways. As already mentioned, the first feedback signal 116or the second feedback signal 118 may be weighted by a weighting factor.For example, the weighted sum may be determined or calculated by addingthe first feedback signal 116 and the second feedback signal 118weighted by a weighting factor c_(weight). This may be equal to anaddition of the first feedback signal weighted by the inverse weightingfactor 1/c_(weight) and the second feedback signal 118 or a subtractionof the second feedback signal weighted by the negative weighting factor−c_(weight) from the first feedback signal 116. In other words, theweighting factor c_(weight) can be selected so that the weighted sum maybe calculated or determined by adding the first feedback signal 116 andthe second feedback signal 118 weighted by a weighting factorc_(weight), adding the first feedback signal 116 weighted by a weightingfactor c_(weight) and the second feedback signal 118, subtracting thefirst feedback signal 116 weighted by a weighting factor c_(weight) fromthe second feedback signal 118 or subtracting the second feedback signal118 weighted by a weighting factor c_(weight) from the first feedbacksignal 116, for example.

The weighting factor may be selected in various ways (e.g. depending onthe type of feedback signal or depending on the way the feedback signalsare derived from the amplified radio frequency transmit signal). Forexample, the weighting factor may be a complex value for complex-valuedfeedback signals. For example, the first feedback signal 116 and thesecond feedback signal 118 may be complex-valued electrical signals inan in-phase/quadrature-phase representation (comprising an in-phasesignal and a quadrature-phase signal) or a polar representation(comprising an amplitude signal and a phase signal).

The first feedback signal 116 or the second feedback signal 118 may beweighted with the weighting factor by multiplying or dividing the firstfeedback signal 116 or the second feedback signal 118 by the weightingfactor, for example.

As already mentioned, the amplified radio frequency transmit signal 112may comprise a frequency bandwidth in the range of a center frequency(e.g. frequency of local oscillator signal for up-conversion of thetransmit signal to the radio frequency domain). In other words, thecenter frequency may be located within the frequency bandwidth of theamplified radio frequency transmit signal 112. In this case, theweighting factor may be constant for a given or constant centerfrequency of the amplified radio frequency transmit signal 112. Forexample, the apparatus 100 may only process radio frequency transmitsignals 102 with the same center frequency or with negligible variation(e.g. less than bandwidth of amplified radio frequency transmit signal)of the center frequency. In this case, the weighting factor may be keptconstant so that the determination of the weighted sum can beimplemented with low effort.

Alternatively, the apparatus 100 may process or transmit radio frequencytransmit signals 102 with various different center frequencies (e.g.within two or more different mobile communication frequency bands) overtime. For example, an up-conversion of a baseband transmit signal may bedone with various local oscillator signals comprising variousfrequencies so that the center frequency of the radio frequency transmitsignal 102 varies over time. In this example, the weighting factor mayvary for different center frequencies. In other words, the weightingfactor may comprise a first value for a first center frequency of anamplified radio frequency transmit signal 112 and may comprise a secondvalue for a second center frequency (different from the first centerfrequency) of an amplified radio frequency transmit signal 112. In thisway, a significant reduction of the influence of an antenna impedancemismatch on the information related to a power variation of theamplified radio frequency transmit signal 112 determined by the powervariation determining module 130 can be obtained for a large frequencyrange.

The weighting factor can be selected so that the weighted sum isindependent of the varying impedance at the antenna module 120 or causesonly a negligible contribution to the weighted sum. In other words, theweighting factor may be selected (e.g. calculated or selected from alookup table) or predefined (e.g. stored by a memory module) so that theportion of the weighted sum depending on a varying impedance at theantenna module is less than 1% (or less than 10%, less than 0.1% or lessthan 0.01%) of the weighted sum or of the power variation indicated bythe power variation signal 132 or the weighted sum (or the powervariation indicated by the power variation signal) is independent of avarying impedance of the antenna module 120. In this way, an accurateinformation on the power variation of the power amplifier module 110without or with negligible influence of an impedance mismatch at theantenna module 120 can be provided.

In other words, the weighting factor may be selected or predefined sothat a portion of the weighted sum depending on a reverse wave signalreflected due to a varying impedance mismatch at the antenna module 120is less than 1% (or less than 10%, less than 0.1% or less than 0.01%) ofthe weighted sum or the weighted sum is independent of the reverse wavesignal reflected due to a varying impedance mismatch at the antennamodule 120.

An example for a possible calculation of a predefined weighting factoror a weighting factor to be selected is described in connection withFIG. 2 below.

The weighting factor may be calculated by the power variationdetermining module 130 (e.g. depending on center frequency or afrequency band of the amplified radio frequency transmit signal) or maybe stored by a memory module and provided for the determination of theweighted sum. In other words, the power variation determining module 130may comprise a memory module for providing the weighting factor (e.g. asingle register or memory address, if the weighting factor is constantin any case). Alternatively, a plurality of weighting factors (e.g. fordifferent center frequencies or frequency bandwidths of the amplifiedradio frequency transmit signal) may be stored by the memory module. Inother words, the power variation determining module 130 may comprise amemory module comprising a stored lookup table (LUT) configured toprovide the weighting factor (e.g. frequency depending). In this way, aconstant weighting factor or a plurality of weighting factors enabling afrequency-dependent selection of a suitable weighting factor can beprovided with low effort.

The apparatus 100 may comprise one or more additional optional elementswithin the transmit path between the power amplifier module 110 and theantenna module 120. For example, the apparatus 100 may comprise aduplexer module (e.g. if the apparatus is used by a transceiver)configured to provide the amplified radio frequency transmit signal 112to the antenna module 120 and to provide signals received by the antennamodule 120 to a receive path or a receiver module.

Optionally, additionally or alternatively, the apparatus 100 maycomprise an antenna switch module within the transmit path between thepower amplifier module 110 and the antenna module 120. The antennaswitch module may switch the amplified radio frequency transmit signal112 to an antenna of the antenna module 120. The antenna module 120 maycomprise a plurality of antennas and the antenna switch module mayswitch the amplified radio frequency transmit signal 112 to one or moreantennas of the plurality of antennas of the antenna module 120, forexample.

Optionally, additionally or alternatively to one or more aspectsmentioned above, the first feedback signal 116 may be derived from theamplified radio frequency transmit signal 112 at a position within thetransmit path between the power amplifier module 110 and the duplexermodule and the second feedback signal 118 may be derived from theamplified radio frequency transmit signal 112 at a position within thetransmit path between the duplexer module and the antenna module 120.Alternatively, the first feedback signal 116 may be derived from theamplified radio frequency transmit signal 112 between the duplexermodule and the antenna switch module and the second feedback signal 118may be derived from the amplified radio frequency transmit signalbetween the antenna switch module and the antenna module 120. In thesecases, the first feedback signal 116 and the second feedback signal 118may be derived by a coupling element capacitively or inductively coupledto the transmit path (e.g. capacitor).

Alternatively, the first feedback signal 116 and the second feedbacksignal 118 may be derived from the amplified radio frequency transmitsignal 112 by a directional coupler located within the transmit pathbetween the power amplifier module 110 and the duplexer module, betweenthe duplexer module and the antenna switch module or between the antennaswitch module and the antenna module 120.

Each of these examples provide two feedback signals with differentdependencies on the varying impedance at the antenna module 120.

The power variation determining module 130 may provide the powervariation signal 132 in order to trigger a warning, if the powervariation of the amplified radio frequency transmit signal 112 exceeds apredefined threshold. Alternatively, the power variation determiningmodule may control a gain of the power amplifier module 110 based on thepower variation signal 132. In this way, a feedback loop can beimplemented so that the power variation of the amplified radio frequencytransmit signal 112 can be kept low.

For this, the power variation signal 132 may be generated in real time(e.g. within a loop time of less than 1 ms) so that the gain control ofthe power amplifier module 110 based on the power variation signal 132may be enabled.

The power amplifier module 110, the antenna module 120 and/or the powervariation determining module 130 may be independent hardware units orpart of a processor, a microcontroller or a digital signal processor ora computer program or a software product for running on a processor, amicrocontroller or a digital signal processor. Further, these modulesmay be manufactured independently of each other or at least partlytogether (e.g. on the same semiconductor die or sharing at least somesame parts of an electric circuit).

FIG. 2 shows a block diagram of an apparatus 200 for determininginformation on a power variation of a transmit signal according to anexample. The apparatus 200 comprises a power amplifier module 210, anantenna module 220, a power variation determining module 230, a feedbackreceiver module 240 and a directional coupler 250. The direction coupler250 is arranged within the transmit path between the power amplifiermodule 210 and the antenna module 220 (e.g. comprising at least oneantenna). The feedback receiver 240 is connected to the directionalcoupler 250. Further, the feedback receiver module 240 is connected tothe power variation determining module 230. The power amplifier module210 comprises a power amplifier 214 (PA) amplifying a radio frequencytransmit signal 202 applied at an input port (RF input signal). Further,the power amplifier module 210 may comprise an optional radio frequencyfront end module 216 (RF FE) for further processing of the amplifiedradio frequency transmit signal 212 (e.g. filtering). The amplifiedradio frequency transmit signal 212 is at least partly provided to theantenna module 220 through the directional coupler 250.

The directional coupler 250 comprises an input port 1, a transmittedport 2, a coupled port 3 and an isolated port 4. The input port 1receives the amplified radio frequency transmit signal 212 and thetransmitted port 2 provides at least partly the amplified radiofrequency transmit signal 212 to the antenna module 220. The coupledport 3 provides a forward-coupled signal 216 mainly caused by theamplified radio frequency transmit signal 212 (e.g. the largest portionof the forward-coupled signal is caused by the amplified radio frequencytransmit signal). Further, the isolated port 4 provides areverse-coupled signal 218 mainly caused by a reverse wave signalreflected due to a varying impedance mismatch at the antenna module 220received by the transmitted port 2 (e.g. the largest signal portion ofthe reverse-coupled signal is caused by the reverse wave signal).

The feedback receiver module 240 generates the first feedback signala_(c) based on the forward-coupled signal 216 and generates the secondfeedback signal b_(c) based on the reverse-coupled signal 218. Forexample, the feedback receiver module 240 generates the first feedbacksignal a_(c) at least by down-conversion (e.g. by a polar demodulator oran in-phase/quadrature-phase demodulator) of the forward-coupled signal216 from a radio frequency domain to a baseband domain of the apparatus200 and generates the second feedback signal b_(c) at least bydown-conversion (e.g. by a polar demodulator or anin-phase/quadrature-phase demodulator) of the reverse-coupled signal 218from the radio frequency domain to the baseband domain of the apparatus200.

Due to the low frequencies in the baseband domain of the apparatus 200(compared to frequencies in the radio frequency domain), informationrelated to a power variation of the amplified radio frequency transmitsignal 212 can be determined with low effort.

In the example shown in FIG. 2, the feedback receiver module 240comprises a first matching and attenuation module 243, a first feedbackreceiver 245 (FBR1) and a first digital-to-analog converter 247 (DAC)for generating the first feedback signal a_(c) based on theforward-coupled signal 216 and a second matching and attenuation module344, a second feedback receiver 246 (FBR2) and a seconddigital-to-analog converter 248 (DAC) for generating the second feedbacksignal b_(c) based on the reverse-coupled signal 218. The feedbackreceiver module 240 receives the forward coupled signal 216 at a firstinput port 5 and the reverse-coupled signal 218 at a second input port 7and provides the first feedback signal a_(c) at a first output port 6and the second feedback signal b_(c) at a second output port 8.

The first matching and attenuation module 243 performs a matching and/orattenuation of the forward-coupled signal 216 (e.g. filtering by afilter and/or amplifying by a low-noise amplifier) and the secondmatching and attenuation module 244 performs a matching and/orattenuation of the reverse-coupled signal 218. The first feedbackreceiver 245 performs at least a down-conversion of the output signal ofthe first matching and attenuation module 243 from a radio frequencydomain of the apparatus 200 to a baseband domain and the second feedbackreceiver 246 performs at least a down conversion of the output signal ofthe second matching and attenuation module 244 from the radio frequencydomain to the baseband domain of the apparatus 200. Further, the firstdigital-to-analog converter 247 converts the analog output signal of thefirst feedback receiver 245 to a digital signal representing the firstfeedback signal a_(c) and the second digital-to-analog converter 248converts the analog output signal of the second feedback receiver 246 toa digital signal representing the second feedback signal b_(c). Due tothe digital-to-analog conversion of the feedback signals, the powervariation determining module 230 can be implemented in the digitaldomain of the apparatus 200.

In other words, optionally, additionally or alternatively to one or moreaspects mentioned above, the power variation determining module 230 maydetermine at least the weighted sum by digital signal processing. Inthis way, the determination of the weighted sum can be implemented withlow effort.

In the example of FIG. 2, the power variation determining module 230comprises an adder 234, a multiplier 236, a memory module 239 and a meanvalue determining module 238. The memory module 239 comprises a storedlookup table (LUT) providing the weighting factor c_(weight) asmentioned above. The multiplier 236 multiplies the second feedbacksignal b_(c) with the weighting factor c_(weight) and the combiner 234calculates the weighted sum s by adding the first feedback signal a_(c)with the second feedback signal b_(c) weighted by the weighting factorc_(weight) outputted by the multiplier 236. The mean value determiningmodule 238 generates the power variation signal 232 based on theweighted sum s so that the power variation signal 232 indicates a meanvalue of the power variation of the amplified radio frequency transmitsignal 212 over time, for example. This power variation may mainlydepend on effects (e.g. temperature influence to gain or filtercharacteristic or frequency influences) different from the impedance atthe antenna module, since this contribution can be kept very low or canbe reduced due to the weighted sum. For example, the mean valuedetermining module 238 determines or calculates the root mean square ofthe weighted sum s and outputs the result by the power variation signal232 or outputs a change of the root mean square of the weighted sum sover time by the power variation signal 232.

The power variation signal 232 may be used as feedback signal for powercontrol, for example. The first feedback signal or resulting forwardwave a_(c) may be a superposition of different contributions. The maincontribution is the desired portion of forward power (e.g. given by γ₁k₁₃ a). However, there may be at least two unwanted contributionscausing a total forward wave a_(c), which depends on antenna load Γ_(L).One contribution is given by the limited isolation of the coupler (˜γ₁k₂₃ b) and the other one is caused by reflection of the coupled reversewave or reverse coupled signal 218 at the non-50Ω termination of thereverse port 7 (˜γ₁ k₂₄ b Γ_(R)). The same or similar is valid for thesecond feedback signal or reverse wave be. Simplified calculationdelivers, for example:

a _(C)=γ₁ [k ₁₃ a+k ₂₃ b+k ₂₄ bΓ _(R)]=γ₁ a[k ₁₃ +k ₂₃Γ_(L) +k₂₄Γ_(L)Γ_(R)]

b _(C)=γ₂ a[k ₂₄Γ_(L) +k ₁₄ +k ₁₃Γ_(F)]

wherein a_(c) is the first feedback signal, b_(c) is the second feedbacksignal, γ₁ is a complex transfer factor from port 5 to port 6, γ₂ is acomplex transfer factor from port 7 to port 8, k₁₃ is a complex couplingfactor between port 1 and port 3, k₂₃ is an isolation factor from port 2to port 3, k₂₄ is a complex coupling factor between port 2 and port 4,k₁₄ is an isolation factor from port 1 to port 4, Γ_(R) is a reflectioncoefficient due to mismatch at port 7, Γ_(F) is a reflection coefficientdue to mismatch at port 5, Γ_(L) is a reflection coefficient due to avarying impedance mismatch at the antenna module (Γ_(L)=b/a), a is theamplified radio frequency transmit signal and b is a reflected signalcaused by a varying impedance mismatch at the antenna module.

The forward wave (first feedback signal) and the reverse wave (secondfeedback signal) can be added. This may be done as vector sum and byweighting the reverse wave with a complex factor c_(weight) prior to theadding procedure.

s=a _(C) +c _(weight) b _(C)=γ₁ a[k ₁₃ +k ₂₃Γ_(L) +k ₂₄Γ_(R)Γ_(L) ]+c_(weight)γ₂ a[k ₂₄Γ_(L) +k ₁₄ +k ₁₃Γ_(F) ]

s=γ ₁ ak ₁₃ +c _(weight)γ₂ a(k ₁₄ +k ₁₃Γ_(F))+aΓ _(L)(γ₁ k ₂₃+γ₁ k₂₄Γ_(R)+γ₂ k ₂₄ c _(weight))

wherein s is the weighted sum and c_(weight) is the weighting factor.

The weighting factor c_(weight) can be selected such the Γ_(L) dependentterm (dependency on the varying impedance at the antenna module) iszero.

${a\; {\Gamma_{L}\left( {{\gamma_{1}k_{23}} + {\gamma_{1}k_{24}\Gamma_{R}} + {\gamma_{2}k_{24}c_{weight}}} \right)}} = {\left. 0\Rightarrow c_{weight} \right. = {\left. \frac{{\gamma_{1}k_{23}} + {\gamma_{1}k_{24}\Gamma_{R}}}{\gamma_{2}k_{24}}\Rightarrow s \right. = {{\gamma_{1}a\; k_{13}} + {const}}}}$

The vectorial edition of forward wave and the complex scaled reversewave results in a sum signal s (weighted sum) which may not depend onantenna load Γ_(L). It may only depend on the forward wave a (theamplified radio frequency transmit signal). This may mean that there isno (or negligible) power variation into VSWR (voltage standing waveratio), for example. The delivered power may be completely (or nearlycompletely) flat across load phase, for example.

Further, the RMS value (root mean square) of the sum signal s may becalculated which can be used as a feedback signal for power controlpurposes.

The complex weighting factor c_(weight) can be determined by front end(FE) specific parameters (e.g. parameters of the hardware configurationor architecture) like coupling factor and isolation. Therefore, theweighting factor could be determined for a given front end configurationbased on a couple of boards (e.g. inlet) or devices and then used overmass production for all devices (e.g. mobile terminals) with the samefront end configuration. In this way, the weighting factor can be easilypredefined for a large number of equal proposed apparatus.

Alternatively, the weighting factor could be determined during factorycalibration (e.g considering manufacturing variations). In this way, theweighting factor c_(weight) would eliminate the term depending on thevarying impedance at the antenna module more accurately so that theportion of the weighted sum depending on the varying impedance at theantenna module may be close to zero or even zero.

Optionally, to improve flatness across band, a frequency-dependentweighting factor c_(weight) may be used. The weighting factors can bestored in a dedicated lookup table. The lookup table entry may then beselected depending on the operating frequency (e.g. center frequency).

The apparatus 200 may comprise one or more optional additional featurescorresponding to one or more aspects mentioned in connection with theproposed concept or one or more examples described above.

FIG. 3 shows a block diagram of an apparatus 300 for determininginformation on a power variation of a transmit signal according to anexample. The apparatus 300 comprises a directional coupler 310 and apower variation determining module 320. The directional coupler 310comprises an input port 312, a transmitted port 314, a coupled port 316and an isolated port 318. The input port 312 receives a radio frequencytransmit signal 302 and the transmitted port 304 provides at leastpartly the radio frequency transmit signal 302 to an antenna module. Thecoupled port 316 provides a forward-coupled signal 324 mainly caused bythe radio frequency transmit signal 302 provided to the input port 312and the isolated port 318 provides a reverse-coupled signal 326 mainlycaused by a reverse wave signal reflected due to a varying impedancemismatch at the antenna module received by the transmitted port 314. Thepower variation determining module 320 generates a power variationsignal 322 comprising information related to a power variation of theradio frequency transmit signal 302 based on a weighted sum of a firstfeedback signal derived from the forward-coupled signal 324 and thesecond feedback signal derived from the reverse-coupled signal 326.

By calculating a weighted sum of two signals derived from a radiofrequency transmit signal 302 but with different dependencies on animpedance at the antenna module, an influence of variations of theimpedance at the antenna module or the weighted sum (e.g. which may varydue to varying environmental conditions) can be kept low or evencompletely removed. In this way, an information on the power variationof the amplified radio frequency transmit signal 302 can be determinedwithout a contribution of the varying impedance at the antenna module orwith negligible contribution of the varying impedance at the antennamodule. In other words, due to the consideration of the weighted sum,information on a power variation for a nearly perfectly or a perfectlymatched antenna module can be provided. Such information may be used forthe control of the gain of a power amplifier module without or withnegligible influence of the variation of the impedance at the antennamodule. In this way, the power variation into mismatch may besignificantly reduced, for example.

The explanations and descriptions provided in connection with theexamples above (e.g. FIGS. 1 and 2) are also applicable to the apparatus300. Especially, explanations related to the information on a powervariation, the radio frequency transmit signal, the forward-coupledsignal, the reverse-coupled signal, the varying impedance at the antennamodule, the power variation determining module, the power variationsignal, the determination of the weighted sum, the first feedback signaland the second feedback signal are correspondingly valid for theapparatus 300, for example.

Optionally, the apparatus 300 may comprise a power amplifier module foramplifying a radio frequency transmit signal to be amplified so that anamplified radio frequency transmit signal is provided to the input port302 of the directional coupler 310.

Further, the apparatus 300 may comprise an antenna module transmittingthe radio frequency transmit signal 302 provided by the transmitted port314.

The apparatus 300 may comprise one or more further optional featurescorresponding to one or more aspects mentioned in connection with theproposed concept or one or more examples described above.

Some examples relate to an apparatus for determining information on apower variation of a transmit signal comprising means for amplifyingsignals, means for transmit signals and means for determining a powervariation. The means for amplifying signals amplify a radio frequencytransmit signal and the means for transmitting signals transmit at leastpartly the amplified radio frequency transmit signal. The means fordetermining a power variation determines a weighted sum of a firstfeedback signal derived from the amplified radio frequency transmitsignal and a second feedback signal derived from the amplified radiofrequency transmit signal. The first feedback signal and the secondfeedback signal comprise different dependencies on a varying impedanceat the means for transmitting signals. Further, the means fordetermining a power variation generates a power variation signal basedon the weighted sum. The power variation signal comprises informationrelated to a power variation of the amplified radio frequency transmitsignal.

The apparatus may comprise one or more additional optional featurescorresponding to one or more aspects mentioned in connection with theproposed concept or one or more examples described above.

Some examples relate to a transmitter or a transceiver comprising anapparatus for determining information on a power variation of a transmitsignal according to the proposed concept or one or more examplesdescribed above.

Further examples relate to a mobile device (e.g. a cell phone, a tabletor a laptop) comprising a transmitter or a transceiver described above.The mobile device or mobile terminal may be used for communicating in amobile communication system.

FIG. 4 shows a schematic illustration of a mobile device 150. The mobiledevice comprises an apparatus 160 for determining information on a powervariation of a transmit signal comprising at least a power amplifiermodule 162, an antenna module 164 and power variation determining module166 as described in connection with the proposed concept or one or moreexamples described above. Further, the mobile device comprises abaseband processor module 170 generating a baseband transmit signalbeing used to provide the radio frequency transmit signal to the poweramplifier module 162. Additionally, the mobile device comprises a powersupply unit 180 supplying at least the apparatus 160 and the basebandprocessor module 170 with power.

The mobile device 100 may provide information of a power variation of anamplified radio frequency transmit signal to be transmitted with low oreven no dependency on a variation of an impedance at the antenna module164 due to the implementation of a proposed apparatus 160. Further, themobile device 100 may provide the amplified radio frequency transmitsignal with low power variation caused by a varying impedance mismatchat the antenna module 164 by using the power variation signal for powercontrol of the power amplifier module 162, for example.

In some examples, a cell phone may comprise a transmitter or atransceiver comprising an apparatus for determining information on apower variation of a transmit signal according to the proposed conceptor one or more examples described above.

Further, some examples relate to a base station or a relay station of amobile communication system comprising a transmitter or a transceiverwith an apparatus for determining information on a power variation of atransmit signal according to the described concept or one or moreexamples described above.

A mobile communication system may, for example, correspond to one of themobile communication systems standardized by the 3rd GenerationPartnership Project (3GPP), e.g. Global System for Mobile Communications(GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE RadioAccess Network (GERAN), High Speed Packet Access (HSPA), UniversalTerrestrial Radio Access Network (UTRAN) or Evolved UTRAN (E-UTRAN),Long Term Evolution (LTE) or LTE-Advanced (LTE-A), or mobilecommunication systems with different standards, e.g. WorldwideInteroperability for Microwave Access (WIMAX) IEEE 802.16 or WirelessLocal Area Network (WLAN) IEEE 802.11, generally any system based onTime Division Multiple Access (TDMA), Frequency Division Multiple Access(FDMA). Orthogonal Frequency Division Multiple Access (OFDMA), CodeDivision Multiple Access (CDMA), etc. The terms mobile communicationsystem and mobile communication network may be used synonymously.

The mobile communication system may comprise a plurality of transmissionpoints or base station transceivers operable to communicate radiosignals with a mobile transceiver. In these examples, the mobilecommunication system may comprise mobile transceivers, relay stationtransceivers and base station transceivers. The relay stationtransceivers and base station transceivers can be composed of one ormore central units and one or more remote units.

A mobile transceiver or mobile device may correspond to a smartphone, acell phone, User Equipment (UE), a laptop, a notebook, a personalcomputer, a Personal Digital Assistant (PDA), a Universal Serial Bus(USB)-stick, a tablet computer, a car, etc. A mobile transceiver orterminal may also be referred to as UE or user in line with the 3GPPterminology. A base station transceiver can be located in the fixed orstationary part of the network or system. A base station transceiver maycorrespond to a remote radio head, a transmission point, an accesspoint, a macro cell, a small cell, a micro cell, a pico cell, a femtocell, a metro cell etc. The term small cell may refer to any cellsmaller than a macro cell, i.e. a micro cell, a pico cell, a femto cell,or a metro cell. Moreover, a femto cell is considered smaller than apico cell, which is considered smaller than a micro cell. A base stationtransceiver can be a wireless interface of a wired network, whichenables transmission and reception of radio signals to a UE, mobiletransceiver or relay transceiver. Such a radio signal may comply withradio signals as, for example, standardized by 3GPP or, generally, inline with one or more of the above listed systems. Thus, a base stationtransceiver may correspond to a NodeB, an eNodeB, a BTS, an accesspoint, etc. A relay station transceiver may correspond to anintermediate network node in the communication path between a basestation transceiver and a mobile station transceiver. A relay stationtransceiver may forward a signal received from a mobile transceiver to abase station transceiver, signals received from the base stationtransceiver to the mobile station transceiver, respectively.

The mobile communication system may be cellular. The term cell refers toa coverage area of radio services provided by a transmission point, aremote unit, a remote head, a remote radio head, a base stationtransceiver, relay transceiver or a NodeB, an eNodeB, respectively. Theterms cell and base station transceiver may be used synonymously. Insome examples a cell may correspond to a sector. For example, sectorscan be achieved using sector antennas, which provide a characteristicfor covering an angular section around a base station transceiver orremote unit. In some examples, a base station transceiver or remote unitmay, for example, operate three or six cells covering sectors of 120°(in case of three cells), 60° (in case of six cells) respectively.Likewise a relay transceiver may establish one or more cells in itscoverage area. A mobile transceiver can be registered or associated withat least one cell, i.e. it can be associated to a cell such that datacan be exchanged between the network and the mobile in the coverage areaof the associated cell using a dedicated channel, link or connection. Amobile transceiver may hence register or be associated with a relaystation or base station transceiver directly or indirectly, where anindirect registration or association may be through one or more relaytransceivers.

Some examples relate to a minimization of power variation into mismatchby means of forward and reverse wave. It is suggested to use asimultaneous evaluation of forward and reflect wave with respect tomagnitude and phase in order to minimize the power variation intomismatch. For this, the vector sum of forward wave and complex-weightedreverse wave can be determined. The complex-weighting factor of thereflected wave can be selected so that the vector sum does not depend onthe antenna load impedance, for example. This may be done in an effortto minimize the power variation into mismatch. In this way, an extremelylow power variation (e.g. smaller than 0.5 dB) can be reached acrossfrequency.

A system using a directional coupler only sensing a portion of theforward power and the subsequent power detection for a power controlloop comprising a power flatness into VSVR limited by the effectivedirectivity. The effective directivity may be given by the intrinsicdirectivity of the coupler, by return loss of forward and reverse portand by limited isolation on board (e.g. coupling between power amplifieroutput and radio frequency feedback line for reverse power). It may bedifficult to achieve a ripple (e.g. into a free 3:1 load) which is lessthan 1 dB although the coupler is located before the antenna. By usingthe proposed concept, the power variation into mismatch may be improvedbeyond a limit given by the effective directivity of the system, forexample.

For example, a proposed apparatus may offer an attractive implementationin all mobile terminals, although it may also be applied in other fields(e.g. base station of communication networks).

FIG. 4 shows a flowchart of a method 400 for determining information ona power variation of a transmit signal. The method 400 comprisesamplifying 410 a radio frequency transmit signal and transmitting 420the amplified radio frequency transmit signal at least partly by anantenna module. Further, the method 400 comprises determining 430 aweighted sum of a first feedback signal derived from the amplified radiofrequency transmit signal and a second feedback signal derived from theamplified radio frequency transmit signal. The first feedback signal andthe second feedback signal comprise different dependencies on a varyingimpedance at the antenna module. Further, the method 400 comprisesgenerating 440 a power variation signal based on the weighted sum sothat the power variation signal comprises information related to a powervariation of the amplified radio frequency transmit signal.

The method 400 may comprise one or more additional optional actscorresponding to one or more aspects mentioned in connection with theproposed concept or one or more examples described above.

FIG. 5 shows a flowchart of a method 500 for determining information ona power variation of a transmit signal with a directional coupler. Thedirectional coupler comprises an input port, a transmitted port, acoupled port and an isolated port. The method 500 comprises receiving510 a radio frequency transmit signal at the input port and providing520 at least partly the radio frequency transmit signal by thetransmitted port to an antenna module. Further, the method 500 comprisesproviding 530 a forward-coupled signal mainly caused by the radiofrequency transmit signal by the coupled port and providing 540 areverse coupled signal by the isolated port mainly caused by a reversewave signal reflected due to a varying impedance mismatch at the antennamodule received by the transmitted port. Additionally, the method 500comprises generating 550 a power variation signal comprising informationrelated to a power variation of the radio frequency transmit signalbased on a weighted sum of the first feedback signal derived from theforward-coupled signal and a second feedback signal derived from thereverse-coupled signal.

The method 500 may comprise one or more additional optional actscorresponding to one or more aspects mentioned in connection with theproposed concept or one or more examples described above.

In the following examples pertain to further examples. Example 1 is anapparatus for determining information on a power variation of a transmitsignal. The apparatus comprises a power amplifier module configured toamplify a radio frequency transmit signal, an antenna module configuredto transmit at least partly the amplified radio frequency transmitsignal and a power variation determining module configured to determinea weighted sum of a first feedback signal derived from the amplifiedradio frequency transmit signal and a second feedback signal derivedfrom the amplified radio frequency transmit signal, wherein the firstfeedback signal and the second feedback signal comprise differentdependencies on a varying impedance at the antenna module, wherein thepower variation determining module is further configured to generate apower variation signal based on the weighted sum, wherein the powervariation signal comprises information related to a power variation ofthe amplified radio frequency transmit signal.

In example 2, the subject matter of example 1 can optionally include thepower variation determining module configured to determine the weightedsum by adding the first feedback signal and the second feedback signalweighted by a weighting factor.

In example 3, the subject matter of example 2 can optionally include theweighting factor being a complex value.

In example 4, the subject matter of example 2 or 3 can optionallyinclude the weighting factor being constant for a constant centerfrequency of the amplified radio frequency transmit signal.

In example 5, the subject matter of any one of examples 2-4 canoptionally include the weighting factor varying for different centerfrequencies.

In example 6, the subject matter of any one of examples 2-5 canoptionally include the weighting factor being selected or predefined sothat a portion of the weighted sum depending on the varying impedance atthe antenna module 120 represents less than 1% of the weighted sum orthe weighted sum is independent of the varying impedance at the antennamodule.

In example 7, the subject matter of any one of examples 2-6 canoptionally include the weighting factor being selected or predefined sothat a portion of the weighted sum depending on a reverse wave signalreflected due to a varying impedance mismatch at the antenna module isless than 1% of the weighted sum or the weighted sum is independent ofthe reverse wave signal reflected due to a varying impedance mismatch atthe antenna module.

In example 8, the subject matter of any one of examples 2-7 canoptionally include the power variation determining module comprising amemory module comprising a stored look-up-table configured to providethe weighting factor.

In example 9, the subject matter of any one of examples 1-8 canoptionally include the first feedback signal and the second feedbacksignal comprising signal portions related to the amplified radiofrequency transmit signal and a reverse wave signal caused by areflection of the amplified radio frequency transmit signal due to avarying impedance mismatch at the antenna module.

In example 10, the subject matter of any one of examples 1-9 canoptionally include the first feedback signal and the second feedbacksignal derived from the amplified radio frequency transmit signal atdifferent positions within a transmit path between the power amplifiermodule and the antenna module.

In example 11, the subject matter of any one of examples 1-10 canoptionally include a duplexer module and an antenna switch module withinthe transmit path between the power amplifier module and the antennamodule, wherein the first feedback signal is derived from the amplifiedradio frequency transmit signal between the power amplifier module andthe duplexer module and the second feedback signal is derived from theamplified radio frequency transmit signal between the duplexer moduleand antenna module, the first feedback signal is derived from theamplified radio frequency transmit signal between the duplexer moduleand the antenna switch module and the second feedback signal is derivedfrom the amplified radio frequency transmit signal between the antennaswitch module and the antenna module or the first feedback signal andthe second feedback signal are derived from the amplified radiofrequency transmit signal by a directional coupler located between thepower amplifier module and the duplexer module, between the duplexermodule and the antenna switch module or between the antenna switchmodule and antenna module.

In example 12, the subject matter of any one of examples 1-11 canoptionally include a directional coupler comprising an input port, atransmitted port, a coupled port and an isolated port, wherein the inputport is configured to receive the amplified radio frequency transmitsignal, wherein the transmitted port is configured to provide at leastpartly the amplified radio frequency transmit signal to the antennamodule, wherein the coupled port is configured to provide a forwardcoupled signal mainly caused by the amplified radio frequency transmitsignal, wherein the isolated port is configured to provide a reversecoupled signal mainly caused by a reverse wave signal reflected due to avarying impedance mismatch at the antenna module received by thetransmitted port, wherein the first feedback signal is based on theforward coupled signal and the second feedback signal is based on thereverse coupled signal.

In example 13, the subject matter of example 12 can optionally include afeedback receiver module configured to generate the first feedbacksignal at least by a down conversion of the forward coupled signal froma radio frequency domain to a baseband domain of the apparatus andconfigured to generate the second feedback signal at least by a downconversion of the reverse coupled signal from the radio frequency domainto the baseband domain of the apparatus.

In example 14, the subject matter of any one of examples 1-13 canoptionally include the power variation determining module configured todetermine the weighted sum by digital signal processing.

In example 15, the subject matter of any one of examples 1-14 canoptionally include the power variation determining module configured togenerate the power variation signal based on a root mean squarecalculation of the weighted sum over a predefined time interval.

In example 16, the subject matter of any one of examples 1-15 canoptionally include the power variation determining module configured tocontrol a gain of the power amplifier module based on the powervariation signal.

In example 17, the subject matter of any one of examples 1-16 canoptionally include the power variation signal generated in real time sothat a gain control of the power amplifier module based on the powervariation signal is enabled.

In example 18, the subject matter of any one of examples 1-17 canoptionally include the radio frequency transmit signal containinginformation intended to be transmitted to a receiver.

Example 19 is an apparatus for determining information on a powervariation of a transmit signal. The apparatus comprises a directionalcoupler comprising an input port, a transmitted port, a coupled port andan isolated port, wherein the input port is configured to receive aradio frequency transmit signal, wherein the transmitted port isconfigured to provide at least partly the radio frequency transmitsignal to an antenna module, wherein the coupled port is configured toprovide a forward coupled signal mainly caused by the radio frequencytransmit signal, wherein the isolated port is configured to provide areverse coupled signal mainly caused by a reverse wave signal reflecteddue to a varying impedance mismatch at the antenna module received bythe transmitted port, and a power variation determining moduleconfigured to generate a power variation signal comprising informationrelated to a power variation of the radio frequency transmit signalbased on a weighted sum of a first feedback signal derived from theforward coupled signal and a second feedback signal derived from thereverse coupled signal.

In example 20, the subject matter of example 19 can optionally include apower amplifier module configured to provide the radio frequencytransmit signal to the input port by amplifying a radio frequencytransmit signal to be amplified.

In example 21, the subject matter of example 19 or 20 can optionallyinclude an antenna module configured to transmit at least partly theradio frequency transmit signal provided by the transmitted port.

Example 19 is an apparatus for determining information on a powervariation of a transmit signal. The apparatus comprises means foramplifying signals configured to amplify a radio frequency transmitsignal, means for transmitting signals configured to transmit at leastpartly the amplified radio frequency transmit signal and means fordetermining a power variation configured to determine a weighted sum ofa first feedback signal derived from the amplified radio frequencytransmit signal and a second feedback signal derived from the amplifiedradio frequency transmit signal, wherein the first feedback signal andthe second feedback signal comprise different dependencies on a varyingimpedance at the means for transmitting signals, wherein the means fordetermining a power variation is further configured to generate a powervariation signal based on the weighted sum, wherein the power variationsignal comprises information related to a power variation of theamplified radio frequency transmit signal.

Example 23 is a transmitter or a transceiver comprising an apparatusaccording to one of the examples 1 to 22.

Example 24 is a mobile device comprising a transmitter or a transceiveraccording to example 23.

Example 25 is a cell phone comprising a transmitter or a transceiveraccording to example 23.

Example 26 is a method for determining information on a power variationof a transmit signal. The method comprises amplifying a radio frequencytransmit signal, transmitting the amplified radio frequency transmitsignal at least partly by an antenna module, determining a weighted sumof a first feedback signal derived from the amplified radio frequencytransmit signal and a second feedback signal derived from the amplifiedradio frequency transmit signal, wherein the first feedback signal andthe second feedback signal comprise different dependencies on a varyingimpedance at the antenna module and generating a power variation signalbased on the weighted sum, wherein the power variation signal comprisesinformation related to a power variation of the amplified radiofrequency transmit signal.

Example 27 is a method for determining information on a power variationof a transmit signal with a directional coupler comprising an inputport, a transmitted port, a coupled port and an isolated port. Themethod comprises receiving a radio frequency transmit signal at theinput port, providing at least partly the radio frequency transmitsignal by the transmitted port to an antenna module, providing a forwardcoupled signal mainly caused by the radio frequency transmit signal bythe coupled port, providing a reverse coupled signal by the isolatedport mainly caused by a reverse wave signal reflected due to a varyingimpedance mismatch at the antenna module received by the transmittedport and generating a power variation signal comprising informationrelated to a power variation of the radio frequency transmit signalbased on a weighted sum of a first feedback signal derived from theforward coupled signal and a second feedback signal derived from thereverse coupled signal.

Example 28 is a machine readable storage medium including program code,when executed, to cause a machine to perform the method of any one ofexamples 26 or 27.

Example 29 is a machine readable storage including machine readableinstructions, when executed, to implement a method or realize anapparatus as implemented by any one of examples 1-27.

Example 30 is a computer program having a program code for performingthe method of examples 26 or 27, when the computer program is executedon a computer or processor.

Examples may further provide a computer program having a program codefor performing one of the above methods, when the computer program isexecuted on a computer or processor. A person of skill in the art wouldreadily recognize that steps of various above-described methods may beperformed by programmed computers. Herein, some examples are alsointended to cover program storage devices, e.g., digital data storagemedia, which are machine or computer readable and encodemachine-executable or computer-executable programs of instructions,wherein the instructions perform some or all of the acts of theabove-described methods. The program storage devices may be, e.g.,digital memories, magnetic storage media such as magnetic disks andmagnetic tapes, hard drives, or optically readable digital data storagemedia. The examples are also intended to cover computers programmed toperform the acts of the above-described methods or (field) programmablelogic arrays ((F)PLAs) or (field) programmable gate arrays ((F)PGAs),programmed to perform the acts of the above-described methods.

The description and drawings merely illustrate the principles of thedisclosure. It will thus be appreciated that those skilled in the artwill be able to devise various arrangements that, although notexplicitly described or shown herein, embody the principles of thedisclosure and are included within its spirit and scope. Furthermore,all examples recited herein are principally intended expressly to beonly for pedagogical purposes to aid the reader in understanding theprinciples of the disclosure and the concepts contributed by theinventor(s) to furthering the art, and are to be construed as beingwithout limitation to such specifically recited examples and conditions.Moreover, all statements herein reciting principles, aspects, andexamples of the disclosure, as well as specific examples thereof, areintended to encompass equivalents thereof.

Functional blocks denoted as “means for . . . ” (performing a certainfunction) shall be understood as functional blocks comprising circuitrythat is configured to perform a certain function, respectively. Hence, a“means for s.th.” may as well be understood as a “means configured to orsuited for s.th.”. A means configured to perform a certain functiondoes, hence, not imply that such means necessarily is performing thefunction (at a given time instant).

Functions of various elements shown in the figures, including anyfunctional blocks labeled as “means”, “means for providing a sensorsignal”, “means for generating a transmit signal.”, etc., may beprovided through the use of dedicated hardware, such as “a signalprovider”, “a signal processing unit”, “a processor”, “a controller”,etc. as well as hardware capable of executing software in associationwith appropriate software. Moreover, any entity described herein as“means”, may correspond to or be implemented as “one or more modules”,“one or more devices”, “one or more units”, etc. When provided by aprocessor, the functions may be provided by a single dedicatedprocessor, by a single shared processor, or by a plurality of individualprocessors, some of which may be shared. Moreover, explicit use of theterm “processor” or “controller” should not be construed to referexclusively to hardware capable of executing software, and mayimplicitly include, without limitation, digital signal processor (DSP)hardware, network processor, application specific integrated circuit(ASIC), field programmable gate array (FPGA), read only memory (ROM) forstoring software, random access memory (RAM), and non-volatile storage.Other hardware, conventional and/or custom, may also be included.

It should be appreciated by those skilled in the art that any blockdiagrams herein represent conceptual views of illustrative circuitryembodying the principles of the disclosure. Similarly, it will beappreciated that any flow charts, flow diagrams, state transitiondiagrams, pseudo code, and the like represent various processes whichmay be substantially represented in computer readable medium and soexecuted by a computer or processor, whether or not such computer orprocessor is explicitly shown.

Furthermore, the following claims are hereby incorporated into theDetailed Description, where each claim may stand on its own as aseparate example. While each claim may stand on its own as a separateexample, it is to be noted that although a dependent claim may refer inthe claims to a specific combination with one or more other claims—otherexamples may also include a combination of the dependent claim with thesubject matter of each other dependent or independent claim. Suchcombinations are proposed herein unless it is stated that a specificcombination is not intended. Furthermore, it is intended to include alsofeatures of a claim to any other independent claim even if this claim isnot directly made dependent to the independent claim.

It is further to be noted that methods disclosed in the specification orin the claims may be implemented by a device having means for performingeach of the respective acts of these methods.

Further, it is to be understood that the disclosure of multiple acts orfunctions disclosed in the specification or claims may not be construedas to be within the specific order. Therefore, the disclosure ofmultiple acts or functions will not limit these to a particular orderunless such acts or functions are not interchangeable for technicalreasons. Furthermore, in some examples a single act may include or maybe broken into multiple sub acts. Such sub acts may be included and partof the disclosure of this single act unless explicitly excluded.

1-22. (canceled)
 23. An apparatus comprising: power amplifier circuitryconfigured to amplify a radio frequency signal to generate a transmitsignal; a directional coupler configured to: receive the transmitsignal; output a portion of the transmit signal to antenna circuitry;receive a reverse signal from the antenna circuitry, the reverse signalcomprising a reflection of the portion of the transmit signal due to animpedance mismatch between the directional coupler and the antennacircuitry; output a reflected signal from the reverse signal; and outputa forward power signal; and power determining circuitry configured togenerate the power feedback signal for the power amplifier from theforward power signal and the reflected signal, where the power feedbacksignal indicates a change of output power of the power amplifier; and alookup table (LUT) coupled to the power determining circuitry, whereinthe power feedback signal is further based on a LUT value in the LUT.24. The apparatus of claim 23 further comprising: the antenna circuitrycoupled to the directional coupler and configured to receive the portionof the transmit signal, reflect the reverse wave signal, and transmit atleast partly the portion of the transmit signal.
 25. The apparatus ofclaim 24 wherein the antenna circuitry comprises an antenna configuredto radiate the transmit portion of the transmit signal.
 26. Theapparatus of claim 23 wherein the directional coupler comprises an inputport, a transmitted port, a coupled port, and an isolated port.
 27. Theapparatus of claim 26 wherein the transmit signal is received at theinput port of the directional coupler; wherein the reverse signal isreceived at the transmitted port of the directional coupler; wherein thecoupled port is configured to output the forward power signal; andwherein the isolated port is configured to output the reflected signal.28. The apparatus of claim 23 wherein a gain of the power amplifier iscontrolled based on the power feedback signal from the power determiningcircuitry.
 29. The apparatus of claim 23 wherein the power determiningcircuitry is further configured to generate a power variation signal,wherein the power variation signal is based on a first feedback signalgenerated from the forward power signal and a second feedback signalgenerated from the reflected signal.
 30. The apparatus of claim 27wherein the power variation signal is further generated as a weightedsum of the first feedback signal and the second feedback signal using aweighting factor.
 31. The apparatus according to claim 30, wherein theweighting factor is constant for a constant center frequency of thetransmit signal.
 32. The apparatus according to claim 30, wherein theweighting factor is predefined to have a portion of the weighted sumdepending on a varying impedance at the antenna circuitry.
 33. Theapparatus according to claim 32, wherein the weighting factor isdetermined from the lookup table (LUT) value stored in a memory of thepower determining circuitry.
 34. An apparatus comprising: an inputinterface configured to receive a reflected signal and a forward powersignal from a directional coupler, wherein the forward power signal isderived from a transmit signal as amplified from a radio frequency (RF)by a power amplifier, and wherein the reflected signal is derived from aportion of the transmit signal reflected by antenna circuitry due to animpedance mismatch between the directional coupler and an antenna; powerdetermining circuitry configured to process the reflected signal and theforward power signal from the communication interface to generate apower feedback signal for a power amplifier from the forward powersignal and the reflected signal, where the power feedback signalindicates a change of an average output power of the power amplifier; alookup table (LUT) coupled to the power determining circuitry, whereinthe power feedback signal is further based on a LUT value in the LUT;and an output interface configured to output the power feedback signalto the power amplifier.
 35. The apparatus of claim 34, wherein theapparatus further comprises the power amplifier; and wherein the poweramplifier is configured to amplify the RF signal to generate thetransmit signal; and wherein a gain of the power amplifier is controlledbased on the power feedback signal from the power determining circuitry.36. The apparatus of claim 34 further comprising the directionalcoupler; wherein the directional coupler comprises an input port, atransmitted port, a coupled port, and an isolated port; wherein thetransmit signal is received at the input port of the directionalcoupler; wherein the a reverse wave signal is received at thetransmitted port of the directional coupler; wherein the coupled port isconfigured to output the forward power signal, and wherein the isolatedport is configured to output the reflected signal.
 37. The apparatus ofclaim 34 wherein the power determining circuitry is further configuredto generate a power variation signal; wherein the power variation signalis based on a first feedback signal generated from the forward powersignal and a second feedback signal generated from the reflected signal,and wherein the power variation signal is further generated as aweighted sum of the first feedback signal and the second feedbacksignal.
 38. The apparatus according to claim 37, wherein a weightingfactor used to generate the weighted sum is constant for a constantcenter frequency of the transmit signal.
 39. The apparatus of claim 23further comprising: the antenna circuitry coupled to the directionalcoupler and configured to receive the portion of the transmit signal,reflect the reverse wave signal, and transmit at least a transmitportion of the transmit signal from the portion of the transmit signal.40. A computer readable storage medium comprising instructions that,when executed by circuitry of a device, cause the device to performoperations for power control of a transmit signal using a power feedbacksignal, the circuitry to: generate a radio frequency (RF) signal;generate a power feedback signal from a reflected signal and a forwardpower signal output from a directional coupler, wherein the forwardpower signal is generated by the directional coupler from a transmitsignal generated from the RF signal by a power amplifier, wherein thereflected signal is generated by the directional coupler from a portionof the transmit signal reflected by antenna circuitry due to animpedance mismatch between the directional coupler and an antenna, andwherein the power feedback signal is generated based on a lookup table(LUT) value from a LUT; and adjust the power control of the poweramplifier for the transmit signal using the power feedback signal. 41.The computer readable storage medium of claim 40, wherein the powervariation signal is based on a first feedback signal generated from theforward power signal and a second feedback signal generated from thereflected signal, and wherein the power variation signal is furthergenerated as a weighted sum of the first feedback signal and the secondfeedback signal.
 42. The computer readable storage medium of claim 40,wherein a weighting factor for the weighted sum is predefined to have aportion of the weighted sum depending on a varying impedance at theantenna circuitry.
 43. An apparatus comprising: power amplifiercircuitry configured to amplify a radio frequency signal to generate atransmit signal; means for generating a reflected signal and a forwardpower signal from the transmit signal and a reverse signal, the reversesignal comprising a reflection of a powertion of the transmit signal dueto an impedance mismatch with antenna circuitry; means for generating alookup table (LUT) value from a LUT; and means for generating a powerfeedback signal for the power amplifier from the forward power signaland the reflected signal, where the power feedback signal indicates achange of output power of the power amplifier.
 44. The apparatus ofclaim 23 further comprising: the antenna circuitry configured to receivethe portion of the transmit signal, reflect the reverse wave signal, andtransmit at least partly the portion of the transmit signal.
 45. Theapparatus of claim 25 wherein the antenna circuitry comprises an antennaconfigured to radiate the transmit portion of the transmit signal. 46.The apparatus of claim 23 wherein a gain of the power amplifier iscontrolled based on the power feedback signal.